Stern drive marine propulsion system including a chain drive mechanism

A stern drive marine propulsion system for a boat, comprising:

• an engine including a rotatable crankshaft, said engine being disposed in the interior of the boat;
• a stern drive lower unit housing adapted for mounting exteriorly of the boat and adjacent the transom of the boat;
• a propeller shaft rotatably mounted in the lower portion of the lower unit housing;
• a propeller mounted to the propeller shaft;
• an input shaft rotatably mounted in the upper portion of the lower unit housing, said input shaft being interconnected with said engine crankshaft so as to be rotatable in response to rotation thereof;
• an intermediate shaft mounted within the lower unit housing, said intermediate shaft being located between the propeller shaft and the input shaft and being substantially parallel to the propeller shaft, and said intermediate shaft being disposed above the waterline during operation of the boat;
• first drive means disposed between said input shaft and said intermediate shaft for transferring rotation of said input shaft to said intermediate shaft;
• second drive means disposed between said propeller shaft and said intermediate shaft for transferring rotation of said intermediate shaft to said propeller shaft, and thereby to said propeller, said second drive means comprising sprocket means associated with said intermediate shaft and said propeller shaft, and chain means drivingly engaged with said sprocket means for transferring rotation of said intermediate shaft to said propeller shaft through said sprocket means;
• selectively engageable reversing means for selectively reversing the direction of rotation of said propeller shaft, and thereby of said propeller;
• wherein said selectively engageable reversing means is located above the waterline during operation of the boat;
• and
• wherein said selectively engageable reversing means comprises:
• a first driving member mounted to said input shaft;
• a first driven member mounted to said intermediate shaft and engageable with said first driving member, said first driving and driven member cooperating to impart rotation to said intermediate shaft in a first rotational direction;
• a second driving member mounted to said input shaft;
• a second driven member mounted to said intermediate shaft and engageable with said second driving member, said second driving and driven members cooperating to impart rotation to said intermediate shaft in a second rotational direction opposite said first rotational direction;
• and
• clutch means for selectively coupling either said first driving and driven members or said second driving and driven members to said intermediate shaft for selectively imparting rotation to said intermediate shaft in either said first rotational direction or said second rotational direction.